1. Field of the Invention
This invention relates in general to earth drilling operations, and in particular, to a head used for grasping and handling pipe.
2. Description of the Prior Art
In earth drilling operations, it becomes necessary at times to transfer stands of pipe including drill pipe tubing and collars between the rotary table and setback or racking area. Because of the large weight of pipe stands, it has been found advantageous to use mechanical devices to transfer pipe between the rotary and the racking area. Mechanical systems are also utilized to handle and rack marine riser pipe used in drilling and producing offshore wells. Mechanical systems are safer, reduce crew fatigue, and allow more positive control. In addition, the transfer time can be decreased, thereby reducing trip time to increase efficiency. As a result, pipe handling systems, including gripping heads have been available for a number of years.
U.S. Pat. No. 3,561,811, issued Feb. 9, 1971, to J. W. Turner, Jr., "Well Pipe Racker", discloses pipe handling equipment including a hook or claw and supporting slide which are operated by fluid pressure to engage drill pipe.
U.S. Pat. No. 4,030,746, issued June 21, 1977, to F. C. Langowski, "Pipe Handling Head", shows a head used to grasp and guide a length of pipe. A hydraulic piston-cylinder arrangement serves to open and close the head.
In the pending application of Paul S. Putnam, et al, entitled "Mechanized Stand Handling Apparatus for Drilling Rigs", Ser. No. 833,145, filed Sep. 14, 1977, a pipe gripping head is shown on an arm driven by linkages, gears, cylinders, and combinations thereof.